/*
 * Licensed to the Apache Software Foundation (ASF) under one
 * or more contributor license agreements.  See the NOTICE file
 * distributed with this work for additional information
 * regarding copyright ownership.  The ASF licenses this file
 * to you under the Apache License, Version 2.0 (the
 * "License"); you may not use this file except in compliance
 * with the License.  You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package org.apache.jena.graph.test;

import java.util.StringTokenizer;

import org.apache.jena.datatypes.xsd.XSDDatatype;
import org.apache.jena.graph.Node;
import org.apache.jena.graph.NodeFactory;
import org.apache.jena.graph.Triple;
import org.apache.jena.shared.JenaException;
import org.apache.jena.shared.PrefixMapping;

/**
 * Creating nodes from string specifications.
 */
public class NodeCreateUtils {
    /**
     * Returns a Node described by the string, primarily for testing purposes. The
     * string represents a URI, a numeric literal, a string literal, a bnode label,
     * or a variable.
     * <ul>
     * <li>'some text' :: a string literal with that text
     * <li>'some text'someLanguage:: a string literal with that text and language
     * <li>'some text'someURI:: a typed literal with that text and datatype
     * <li>digits :: a literal [OF WHAT TYPE] with that [numeric] value
     * <li>_XXX :: a bnode with an AnonId built from _XXX
     * <li>?VVV :: a variable with name VVV
     * <li>&PPP :: to be done
     * <li>name:stuff :: the URI; name may be expanded using the Extended map
     * </ul>
     *
     * @param x the string describing the node
     * @return a node of the appropriate type with the appropriate label
     */
    public static Node create(String x) {
        return create(PrefixMapping.Extended, x);
    }

    /**
     * Returns a Node described by the string, primarily for testing purposes. The
     * string represents a URI, a numeric literal, a string literal, a bnode label,
     * or a variable.
     * <ul>
     * <li>'some text' :: a string literal with that text
     * <li>'some text'someLanguage:: a string literal with that text and language
     * <li>'some text'someURI:: a typed literal with that text and datatype
     * <li>digits :: a literal [OF WHAT TYPE] with that [numeric] value
     * <li>_XXX :: a bnode with an AnonId built from _XXX
     * <li>?VVV :: a variable with name VVV
     * <li>&PPP :: to be done
     * <li>name:stuff :: the URI; name may be expanded using the Extended map
     * </ul>
     *
     * @param pm the PrefixMapping for translating pre:X strings
     * @param x the string encoding the node to create
     * @return a node with the appropriate type and label
     */
    public static Node create(PrefixMapping pm, String x) {
        if ( x.equals("") )
            throw new JenaException("Node.create does not accept an empty string as argument");
        char first = x.charAt(0);
        if ( first == '\'' || first == '\"' )
            return newStringNode(pm, first, x);
        if ( Character.isDigit(first) )
            return NodeFactory.createLiteralDT(x, XSDDatatype.XSDinteger);
        if ( first == '_' )
            return NodeFactory.createBlankNode(x);
        if ( x.equals("??") )
            return Node.ANY;
        if ( first == '?' )
            return NodeFactory.createVariable(x.substring(1));
        if ( first == '&' )
            return NodeFactory.createURI("q:" + x.substring(1));
        int colon = x.indexOf(':');
        String d = pm.getNsPrefixURI("");
        return colon < 0 ? NodeFactory.createURI((d == null ? "eh:/" : d) + x) : NodeFactory.createURI(pm.expandPrefix(x));
    }

    private static String unEscape(String spelling) {
        if ( spelling.indexOf('\\') < 0 )
            return spelling;
        StringBuilder result = new StringBuilder(spelling.length());
        int start = 0;
        while (true) {
            int b = spelling.indexOf('\\', start);
            if ( b < 0 )
                break;
            result.append(spelling.substring(start, b));
            result.append(unEscape(spelling.charAt(b + 1)));
            start = b + 2;
        }
        result.append(spelling.substring(start));
        return result.toString();
    }

    private static char unEscape(char ch) {
        switch (ch) {
            case '\\' :
            case '\"' :
            case '\'' :
                return ch;
            case 'n' :
                return '\n';
            case 's' :
                return ' ';
            case 't' :
                return '\t';
            default :
                return 'Z';
        }
    }

    public static Node literal(PrefixMapping pm, String spelling, String langOrType) {
        String content = unEscape(spelling);
        int colon = langOrType.indexOf(':');
        return colon < 0
            ? NodeFactory.createLiteralLang(content, langOrType)
            : NodeFactory.createLiteralDT(content, NodeFactory.getType(pm.expandPrefix(langOrType)));
    }

    public static Node newStringNode(PrefixMapping pm, char quote, String nodeString) {
        int close = nodeString.lastIndexOf(quote);
        return literal(pm, nodeString.substring(1, close), nodeString.substring(close + 1));
    }

    /**
     * Utility factory as for create(String), but allowing the PrefixMapping to be
     * specified explicitly.
     */
    public static Triple createTriple(PrefixMapping pm, String fact) {
        StringTokenizer st = new StringTokenizer(fact);
        Node sub = create(pm, st.nextToken());
        Node pred = create(pm, st.nextToken());
        Node obj = create(pm, st.nextToken());
        return Triple.create(sub, pred, obj);
    }

    /**
     * Utility factory method for creating a triple based on the content of an "S P
     * O" string. The S, P, O are processed by Node.create, see which for details of
     * the supported syntax. This method exists to support test code. Nodes are
     * interpreted using the Standard prefix mapping.
     */

    public static Triple createTriple(String fact) {
        return createTriple(PrefixMapping.Standard, fact);
    }
}
